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    Subject[PATCH] tpm: Do not dereference NULL pointer if acpi_os_map_memory() fails.
    In drivers/char/tpm/tpm_acpi.c::read_log() we call
    acpi_os_map_memory(). That call may fail for a number of reasons
    (invalid address, out of memory etc). If the call fails it returns
    NULL and we just pass that to memcpy() unconditionally, which will go
    bad when it tries to dereference the pointer.

    Unfortunately we just get NULL back, so we can't really tell the user
    exactely what went wrong, but we can at least avoid crashing and
    return an error (-EIO seemed more generic and more suitable here than
    -ENOMEM or something else, so I picked that).

    Signed-off-by: Jesper Juhl <>
    drivers/char/tpm/tpm_acpi.c | 5 +++++
    1 file changed, 5 insertions(+)

    note: this patch is against git:// v3.6-rc1-tpmdd-staging

    diff --git a/drivers/char/tpm/tpm_acpi.c b/drivers/char/tpm/tpm_acpi.c
    index a1bb5a18..fe3fa94 100644
    --- a/drivers/char/tpm/tpm_acpi.c
    +++ b/drivers/char/tpm/tpm_acpi.c
    @@ -96,6 +96,11 @@ int read_log(struct tpm_bios_log *log)
    log->bios_event_log_end = log->bios_event_log + len;

    virt = acpi_os_map_memory(start, len);
    + if (!virt) {
    + kfree(log->bios_event_log);
    + printk("%s: ERROR - Unable to map memory\n", __func__);
    + return -EIO;
    + }

    memcpy(log->bios_event_log, virt, len);


    Jesper Juhl <>
    Don't top-post
    Plain text mails only, please.

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